1. Technical Field
The present invention relates to a print control device that controls a printing unit in a printing apparatus, to a printing apparatus and to a print control method for a printing apparatus.
2. Related Art
For example, a printing apparatus that is equipped with a plurality of print heads that eject ink is disclosed in JP-A-2004-25551. In this printing apparatus, a plurality of print heads and a plurality of driving control units that control driving of the plurality of print heads are mounted on a carriage provided so as to be capable of reciprocating. Furthermore, a plurality of data processing units that transfer data to the individual driving control units are mounted in the main body of the printing apparatus. A plurality of circuit sets each consisting of one driving control unit and one data processing unit are connected to every predetermined number of print heads in a main control unit that controls reciprocation of the carriage. Since a configuration is adopted in which processing is allocated to one circuit set for every predetermined number of print heads, with this printing apparatus, the processing load on each data processing unit is reduced.
Furthermore, in the case where there are a large number of print heads, a printing apparatus configuration may be adopted in which two or more main control units are provided and a print control device, in which a main control unit, a data processing unit and a driving control unit form a circuit set, is formed on a single substrate. This substrate is then provided in a plurality. By adopting this configuration for a printing apparatus, since a plurality of print control devices are allocated with and control a large number of recording heads, as the number of recording heads increases, the number of print control devices also increases, whereby the load on each print control device remains relatively small and the required printing speed can be ensured.
Furthermore, in the case where a configuration is adopted in which individual print control devices that are in charge of a plurality of recording heads and a driving control device that controls driving of a carriage and transporting of a print medium (sheet) are formed separately and the individual print control devices transmit commands acquired from print data to the driving control device, it is necessary to synchronize the timings at which commands are output from the individual print control devices to the driving control unit. For example, one print control device is made the master (master-side print control device) and another print control device is made the slave (slave-side print control device). Then, a configuration is adopted in which, at a stage when a command to be output by the master-side print control device and a command to be output by the slave-side print control device are both present, the individual print control devices transmit these commands to the driving control device (mechanical controller or the like) of the carriage system and the transport system in synchronization with each other. With such a configuration, it becomes possible to control ink ejection processing for individual recording heads that are individually controlled by the print control devices and transport processing for a printing medium controlled by the driving control device to be at suitable timings.
In addition to a plurality of recording heads being allocated to a plurality of print control devices, it is preferable that components included in the printing apparatus in a plurality, such as a plurality of ink cartridges that supply ink to the recording heads and nozzle testing devices that test for clogging of the nozzles of the recording heads, be allocated to and connected to a plurality of print control devices and that their loads be allocated among the individual print control devices. Here, typically, memory elements, into which ink-related information such as the amounts of ink remaining and ink colors has been written, are provided in the ink cartridges and the individual print control devices are allocated with and manage the ink-related information such as the amount of ink remaining for each ink by accessing the memory elements of the ink cartridges they are in charge of.
Sometimes cases occur where commands (internal commands) are individually generated in only a certain print control device. For example, an error in a component such as a recording head, ink cartridge, nozzle testing device or the like that a print control device is in charge of such as an out of ink error (end of ink error) or a clogged nozzle error for a nozzle testing device in an ink cartridge that a print control device is in charge of, is an example of an internal command generated within the print control device.
However, for example, if an internal command is generated by a master-side print control device, an internal command is not generated by the other slave-side print control device. Consequently, there is a problem in that when one print control device needs to attain synchronization in order to output an internal command, since the command is not present in the other print control device, the internal command cannot be output.
Furthermore, internal commands may include commands for detecting the states of devices or the states of components such as ink cartridges or the like and for making notification of an OK state or an NG state in response to a detection result in order to cause the printing apparatus to perform a predetermined operation such as when initiating the printing apparatus or when an ink cartridge is to be replaced. In this case, upon receiving an OK state command as a notification in the case of an OK state, a driving control device performs control to initiate a predetermined operation unit or on the other hand upon receiving an NG state command in the case of an NG state, the driving control device performs control so as not to initiate the operation unit, and generally if an operation unit has already been initiated the operation unit is stopped.
For example, in the case where there is an OK state in one print control device and an NG state in the other print control device, if the operation unit is stopped, then the driving control device should not initiate the operation unit and if the operation unit has been initiated, then the driving control device should stop the operation unit. If a configuration is adopted in which commands from both sides are separately transmitted to the driving control device, there is a problem in that, when an OK state command has been transmitted, inconvenience is caused such that an operation unit that should not be initiated is initiated. Furthermore, when the timings at which commands are output are synchronized between a plurality of print control devices, there is a problem in that a command transmission error occurs due to a command not being present in all the print control devices.